Single-point incremental forming is an innovative flexible and inexpensive technique to form sheet products when prototypes or small batches are required. The process allows complex geometries to be produced using a computer numerical control machine, eliminating the need for a special die. This study reports on the effects of four important single-point incremental forming process parameters on produced surface profile accuracies. The profile accuracy was estimated by measuring the side angle errors and surface roughness and also waviness and circularity of the product inner surface. Full factorial design of experiments was used to plan the study, and the analysis of variance was used to analyze and interpret the results. The results indicate that the tool diameter (<i>d</i>), step depth (<i>s</i>), and sheet thickness (<i>t</i>) have significant effects on the produced profile accuracy, while the feed rate (<i>f</i>) is not significant. As a general rule, thin sheets with greater tool diameters yielded the best surface quality. The results also show that controlling all surface quality features is complex because of the contradicting effects of, and interactions between, a number of the process parameters.

Abdulmajeed Dabwan

Adham E. Ragab

Mohamed A. Saleh

Saqib Anwar

Atef M. Ghaleb

Ateekh Ur Rehman

Study of the Effect of Process Parameters on Surface Profile Accuracy in Single-Point Incremental Sheet Forming of AA1050-H14 Aluminum Alloy

Over the past few decades, tactile sensors have become an emerging field of research in both academia and industry. Recent advances have demonstrated application of tactile sensors in the area of biomedical engineering and opened up new opportunities for building multifunctional electronic skin (e-skin) which is capable of imitating the human sense-of-touch for medical purposes. Analyses have shown that current smart tactile sensing technology has the advantages of high performance, low-cost, time efficiency, and ease-of-fabrication. Tactile sensing systems have thus sufficiently matured for integration into several fields related to biomedical engineering. Furthermore, artificial intelligence has the potential for being applied in human-machine interfacing, for instance, in medical robotic manipulation, especially during minimally invasive robotic surgery, where tactile sensing is usually a problem. In this survey, we present a comprehensive review of the state of the art of tactile sensors. We focus on the technical details of transduction mechanisms such as piezoresistivity, capacitance, piezoelectricity, and triboelectric and highlight the role of novel and commonly used materials in tactile sensing. In addition, we discuss contributions that have been reported in the field of biomedical engineering, which includes its present and future applications in building multifunctional e-skins, human-machine interfaces, and minimally invasive surgical robots. Finally, some challenges and notable improvements that have been made in the technical aspects of tactile sensing systems are reported.

Yousef Al-Handarish

Olatunji Mumini Omisore

Tobore Igbe

Shipeng Han

Hui Li

Wenjing Du

Jinjie Zhang

Lei Wang

A Survey of Tactile-Sensing Systems and Their Applications in Biomedical Engineering

Due to the low hydration rate of high-volume fly ash (HVFA) concrete at early age, the temperature gradient between the concrete core and surfaces could be effectively reduced. However, the low hydration rate results in a lack of hydration degree for early-age HVFA concrete. Thus, during curing, compared to the strength of ordinary Portland cement (OPC), a subsequent lower one of HVFA concrete leads to a more sensitive response to inner stresses induced by thermal and moisture loads. Based on ABAQUS, in this paper, user subroutines in the temperature and moisture fields were developed, with regard to the hydration degree, for simulation of the temperature and moisture influences on concrete. Additionally, the Double Power Law (DPL) model was used to depict early-age deformations of concrete in the mechanical field. Combined with the extended finite element method (XFEM), another subroutine for early-age cracking analysis in the mechanical field was then developed. Together with aforementioned subroutines, a thermo-hygro-mechanical model is derived. For evaluation of early-age cracking initiation and propagation of a pier composed of HVFA concrete, the model was implemented with XFEM. The obtained results show that (1) temperature and restraints are the main causes of cracking; (2) moisture loss affects surface cracks on structures at early age; and (3) although the temperature difference between the core and surfaces is not much obvious due to the reduced rate of heat dissipation from hydration, cracking of early-age HVFA concrete is still likely to happen for its low early strength. Thus, timely curing is critical to prevent early cracking.

Wei Cui

Yanjun Luo

Shuang Peng

Early-Age Cracking Analysis of a HVFA Concrete Structure Based on Thermo-Hygro-Mechanical Modeling Combined with XFEM

In this paper, the effect of the fiber/matrix interface properties on the tensile and fatigue behavior of 2D woven SiC/SiC ceramic-matrix composites (CMCs) is investigated. The relationships between the interface parameters of the fiber/matrix interface debonding energy and interface frictional shear stress in the interface debonding region and the composite tensile and fatigue damage parameters of first matrix cracking stress, matrix cracking density, and fatigue hysteresis-based damage parameters are established. The effects of the fiber/matrix interface properties on the first matrix cracking stress, matrix cracking evolution, first and complete interface debonding stress, fatigue hysteresis dissipated energy, hysteresis modulus, and hysteresis width are analyzed. The experimental first matrix cracking stress, matrix cracking evolution, and fatigue hysteresis loops of SiC/SiC composites are predicted using different interface properties.

Longbiao Li

Effect of Interface Properties on Tensile and Fatigue Behavior of 2D Woven SiC/SiC Fiber-Reinforced Ceramic-Matrix Composites

For indirect ceramic additive manufacturing (AM), green parts&#x2019; initial densities are low, limiting the postprocessing strengthening under atmospheric pressure. This study employed binder jetting printing (BJP) based on the polycondensation curing of urea-formaldehyde resin to produce series of Al<sub>2</sub>O<sub>3</sub> green specimens with controllable structures. Further, an integrated postprocessing procedure, including the sequential stages of presintering, ceramic slurry infiltration, and final sintering, was conducted on these green specimens with designed structural characteristics for verifying strengthening mechanism. Using a self-developed BJP machine system and the related material which are flexible in process, this study printed green specimens with strong bonding (flexural strength above 6.84 MPa), additionally can regulate their initial densities within the wide range between 21.7&#x0025;&#x223c;43.9&#x0025;. Infiltrated with ceramic slurry, low-density green specimens were significantly strengthened via final sintering, realizing final densities, flexural strength, and compressive strength of 73.2&#x0025;, 43.15&#x2009;MPa, and 331.17&#x2009;MPa, respectively. In comparison, high-density specimens performing poor infiltration obtained limited density increment after final sintering, but better mechanical properties and surface strengthening were realized, exhibiting final densities, flexural strength, comprehensive strength, surface roughness <i>Ra</i>, and Vickers hardness of 70.1&#x0025;, 63.22&#x2009;MPa, 450.18&#x2009;MPa, 9.73&#x2009;<i>&#x3bc;</i>m, and 4.58&#x2009;GPa, respectively. In summary, this study is helpful to provide the technical reference for custom AM ceramic green parts and the postprocessing optimization.

Shu Cao

Fangxia Xie

Xueming He

Chaofeng Zhang

Meiping Wu

Postprocessing Study for the Controllable Structures of Ceramic Green Parts Realized by a Flexible Binder Jetting Printing (BJP) Solution

Soil-water characteristic curve (SWCC) is a key constitutive relationship for studying unsaturated soil, and as is known, microstructure of the soil has great influence on the mechanical behaviour of the soil. In this study, the wetting and drying soil-water characteristic curves (SWCCs) of loess compacted at three different water contents were measured using the filter paper method. And microproperties of compacted loess were obtained by the mercury intrusion method (MIP) and scanning electron microscope (SEM). Results show that the compaction water contents have significant influence on the SWCC and microstructure. The pore size distribution (PSD) curves have great differences in macropore range and are similar in micropore range. Loess compacted at optimum and dry of optimum are generally connected, while there are certain number of nonintruded pores in loess compacted at wet of optimum. The SWCC curves vary significantly in low suction (<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-3.29111pt" id="M1" height="9.25202pt" version="1.1" viewBox="-0.0498162 -5.96091 12.2477 9.25202" width="12.2477pt"><g transform="matrix(.013,0,0,-0.013,0,0)"><path id="g113-118" d="M515 96L502 119C471 88 431 62 423 62C416 62 411 70 417 101C440 223 469 341 497 448H486L412 422L380 277C330 188 210 57 152 57C137 57 126 69 139 124L195 366C210 431 205 448 182 448C155 448 89 413 23 350L36 326C73 354 103 376 112 376C118 376 118 365 113 340L61 118C54 90 52 68 52 51C52 0 75 -12 98 -12S151 -3 181 17C242 58 305 119 362 193H364L345 104C323 3 339 -12 359 -12C390 -12 464 35 515 96Z"/></g><g transform="matrix(.0091,0,0,-0.0091,6.929,3.132)"><path id="g50-98" d="M490 97L476 124C442 96 405 70 398 70C392 70 390 78 396 114C419 243 448 379 463 432L457 436C446 436 431 439 418 442C393 447 368 451 343 451C281 451 204 418 155 381C74 320 24 206 24 107C24 23 59 -12 88 -12C118 -12 155 5 191 34C236 70 290 122 328 177H330L312 84C296 0 311 -12 331 -12C355 -12 425 24 490 97ZM374 387C371 367 360 299 347 264C323 202 187 53 142 53C128 53 113 73 113 120C113 224 157 332 221 380C241 395 274 403 303 403C330 403 360 395 374 387Z"/></g></svg> − <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-3.29111pt" id="M2" height="9.25202pt" version="1.1" viewBox="-0.0498162 -5.96091 14.1476 9.25202" width="14.1476pt"><g transform="matrix(.013,0,0,-0.013,0,0)"><use xlink:href="#g113-118"/></g><g transform="matrix(.0091,0,0,-0.0091,6.929,3.132)"><path id="g50-120" d="M698 334C698 397 680 451 655 451C627 451 602 424 602 397C602 389 605 383 614 371C622 360 624 340 624 317C624 161 546 47 458 47C419 47 389 69 389 125C389 142 391 162 397 185L457 430L451 435L380 421L315 164C301 107 266 47 222 47C182 47 153 69 153 126C153 137 157 162 161 185C166 214 179 265 197 334C203 358 208 385 208 407C208 433 201 451 176 451C124 451 64 404 24 348L44 320C86 366 113 382 121 382C126 382 128 381 128 374C128 368 126 356 122 341C102 266 88 204 81 164C77 143 73 121 73 107C73 23 131 -12 187 -12C234 -12 281 10 322 45C343 5 383 -12 422 -12C559 -12 698 174 698 334Z"/></g></svg> &lt; 1000 kPa) and tend to converge together in high suction (<svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-3.29111pt" id="M3" height="9.25202pt" version="1.1" viewBox="-0.0498162 -5.96091 12.2477 9.25202" width="12.2477pt"><g transform="matrix(.013,0,0,-0.013,0,0)"><use xlink:href="#g113-118"/></g><g transform="matrix(.0091,0,0,-0.0091,6.929,3.132)"><use xlink:href="#g50-98"/></g></svg> − <svg xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg" style="vertical-align:-3.29111pt" id="M4" height="9.25202pt" version="1.1" viewBox="-0.0498162 -5.96091 14.1476 9.25202" width="14.1476pt"><g transform="matrix(.013,0,0,-0.013,0,0)"><use xlink:href="#g113-118"/></g><g transform="matrix(.0091,0,0,-0.0091,6.929,3.132)"><use xlink:href="#g50-120"/></g></svg> ≥ 1000 kPa). Hysteresis in the SWCCs is more obvious for loess compacted at optimum and dry of optimum in the matric suction of 0∼100 kPa; however, there is a pronounced hysteresis for loess compacted at wet of optimum in full matric suction range. The characteristic of the SWCCs including their hysteresis can be well interpreted from the loess microstructure.

Xiao Xie

Ping Li

Xiaokun Hou

Tonglu Li

Guowei Zhang

Microstructure of Compacted Loess and Its Influence on the Soil-Water Characteristic Curve

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<p><em>Advances in Materials Science and Engineering </em>publishes research in all areas of materials science and engineering, including the synthesis and properties of materials, and their applications in engineering applications.</p>


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<p>Chief Editor, Amit Bandyopadhyay, is based at Washington State University and is interested in &nbsp;the fields of additive manufacturing or 3D printing of advanced materials. His current research is focused on metal additive manufacturing, biomedical devices and multi‑materials structures.</p>


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Advances in Materials Science and Engineering